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19th August 2013 Bio 334 - Neurobiology I - Organization of the nervous system 1
Organization of the nervous system 2
Raghav RajanBio 334 – Neurobiology I
August 22nd 2013
19th August 2013 Bio 334 - Neurobiology I - Organization of the nervous system 2
Orienting within the brain – absolute axes and relative axes
ANTERIOR(in front)
POSTERIOR(behind)
INFERIOR(below)
SUPERIOR(above)
● Anterior/Posterior, Superior/Inferior – absolute axis system
● Rostral/Caudal, Dorsal/Lateral – relative to the long axis of the brain or spinal cord
http://www.rci.rutgers.edu/~uzwiak/AnatPhys/APFallLect19.html
19th August 2013 Bio 334 - Neurobiology I - Organization of the nervous system 3
Medial – lateral axes
MEDIAL(near the midline)
LATERAL(away
from the midline)
LATERAL(away
from the midline)
Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007) – Chapter 7
19th August 2013 Bio 334 - Neurobiology I - Organization of the nervous system 4
Ipsilateral and contralateral – things on the same side or the opposite side
IPSILATERAL (same side)
CONTRALATERAL (opposite side)
Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007) – Chapter 7
19th August 2013 Bio 334 - Neurobiology I - Organization of the nervous system 5
Planes of brain sections
Kandel, Schwartz and Jessell, Principles of Neural Science
19th August 2013 Bio 334 - Neurobiology I - Organization of the nervous system 6
Divisions of the nervous system
http://serendip.brynmawr.edu/exchange/brains/structures
19th August 2013 Bio 334 - Neurobiology I - Organization of the nervous system 7
Basal ganglia are a set of nuclei within the brain
● Clearly distinguishable cluster of neurons usually deep in the brain
● Shows up as a some gray matter often surrounded by white matter
Kandel, Schwartz and Jessell, Principles of Neural Science
19th August 2013 Bio 334 - Neurobiology I - Organization of the nervous system 8
Basal ganglia consist of 4 nuclei
● Striatum
● Pallidum
● Substantia nigra
● Subthalamic nucleus
Kandel, Schwartz and Jessell, Principles of Neural Science
19th August 2013 Bio 334 - Neurobiology I - Organization of the nervous system 9
The basal ganglia form loops with the cortex and thalamus
● Cortex - Basal ganglia-thalamus – cortex loops are important in the initiation and selection of movements
● Normal function disrupted in many diseases – Parkinson's disease, Huntington's disease
● Multiple parallel loops involved in other functions too
Kandel, Schwartz and Jessell, Principles of Neural Science
19th August 2013 Bio 334 - Neurobiology I - Organization of the nervous system 10
They are involved in movement selection and movement initiation
● Two pathways:
● Direct pathway – initiates movements
● Indirect pathway – suppresses movements
● Recent optogenetic experiments show this very nicely
– Supplementary videos 2 and 3 from http://www.nature.com/nature/journal/v466/n7306/full/nature09159.html#supplementary-information
Yin and Knowlton, The role of the basal ganglia in habit formation. Nature Reviews Neuroscience (2006)http://www.nature.com/nrn/journal/v7/n6/fig_tab/nrn1919_F1.html
19th August 2013 Bio 334 - Neurobiology I - Organization of the nervous system 11
Songbirds have served as a good model system for understanding the function of these loops
● Evolutionarily conserved – neuronal morphology, molecular markers, activity patterns, connections
● Specialized portion of this loop appears to be involved only in song learning
http://www.nbb.cornell.edu/goldberg/Doupe AJ et al. Songbirds could teach basal ganglia research a new song. Trends in Neurosciences 2005
19th August 2013 Bio 334 - Neurobiology I - Organization of the nervous system 12
This loop is important for learning and is involved in generating variability required for learning
● Learning of complex movement sequences requires three steps
– Exploration using variability
– A mechanism to decide “good” and “bad” outcomes
– Selectively re-inforce “good” outcomes
Doupe AJ et al. Songbirds could teach basal ganglia research a new song. Trends in Neurosciences 2005
19th August 2013 Bio 334 - Neurobiology I - Organization of the nervous system 13
Basal ganglia loops are thought to form parallel circuits that have a number of other functions too
● Parallel loops with high degree of organization
Kandel, Schwartz and Jessell, Principles of Neural Science
19th August 2013 Bio 334 - Neurobiology I - Organization of the nervous system 14
Hippocampus and associated structures are involved in learning and memory
Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007) – Chapter 7
19th August 2013 Bio 334 - Neurobiology I - Organization of the nervous system 15
H.M. (Henry Molaison) revolutionized our understanding of function of hippocampus
● Surgery when he was 27
● Died at the age of 82
● Could not form new memories
● Only some types of memories were affected
● Could remember most things from before surgery
● CAVEAT: Lesions encompass larger area than just hippocampus
http://en.wikipedia.org/wiki/Henry_MolaisonMark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007) – Chapter 7
19th August 2013 Bio 334 - Neurobiology I - Organization of the nervous system 16
Diencephalon gives rise to thalamus and hypothalamus
Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007) – Chapter 7
19th August 2013 Bio 334 - Neurobiology I - Organization of the nervous system 17
Thalamus is the “gateway” to the cortex
● All sensory (except olfactory) are relayed to the cortex through the thalamus
● Thalamo-cortico-thalamic loops are believed to be important for consciousness
Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007) – Chapter 7
19th August 2013 Bio 334 - Neurobiology I - Organization of the nervous system 18
Midbrain gives rise to tectum and tegmentum
● Tectum consists of superior and inferior colliculus
● Superior Colliculus gets information from eye and controls eye movements
● Inferior colliculus gets information from the ears
Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007) – Chapter 7
19th August 2013 Bio 334 - Neurobiology I - Organization of the nervous system 19
Midbrain gives rise to tectum and tegmentum
● Tegmentum consists of red nucleus and substantia nigra
● Both are involved in controlling voluntary movement
● Corticospinal tract passes through the midbrain
Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007) – Chapter 7
19th August 2013 Bio 334 - Neurobiology I - Organization of the nervous system 20
Rostral hindbrain gives rise to cerebellum and pons
Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007) – Chapter 7
19th August 2013 Bio 334 - Neurobiology I - Organization of the nervous system 21
Caudal hindbrain gives rise to medulla
Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007) – Chapter 7
19th August 2013 Bio 334 - Neurobiology I - Organization of the nervous system 22
Cerebellum is again involved in modifying movements
● Gets detailed motor information through the pons about the commands that have been sent out from cerebral cortex
● Receives sensory information from the spinal cord about body position, etc
● Can then compare and adjust movements
● Lesions result in uncoordinated movements
Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007) – Chapter 7
19th August 2013 Bio 334 - Neurobiology I - Organization of the nervous system 23
Pons – a “switchboard” for the cerebellum
● Carries information from cerebral cortex to cerebellum
● Also controls a number of vital functions like breathing, sleep, bladder control, swallowing, etc.
Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007)
19th August 2013 Bio 334 - Neurobiology I - Organization of the nervous system 24
Medulla -
● Has motor neurons that control the tongue
● Receives a lot of sensory information from various senses
● A number of other autonomous functions
Mark F Bear, Barry W Connors, Michael A Paradiso. Neuroscience: Exploring the brain (2007)